Preheat the oven to 180ºc/160ºc fan and line a 9x9″ square baking tray with parchment paper.
Melt together the butter, dark chocolate and the 150g Toblerone in a heatproof bowl over a pan of boiling water, on the microwave in 20-second bursts until melted. Leave on the side to cool whilst you do the rest.
Whisk together the eggs and sugar for a few minutes until the colour has turned pale, is very mousse like, and is double the original volume
When whisked, pour the cooled chocolate mix over eggs and fold together carefully.
Once completely combined, add the cocoa powder and plain flour on top of the chocolate mix and then fold together again
Once combined well, fold through the 400g Toblerone chunks and pour into the prepared tin
Bake in the oven for 25-30+ minutes, or until there is a small wobble in the middle of the tin! Once baked, leave to cool in the tin completely.
If you want that epic fudgy texture, you can wait for them to cool and then 'set' them in the fridge for 1-2+ hours and cut them up after
Notes
This recipe lasts for 5-7+ day at room temperature or in the fridge
These brownies can freeze for 3+ months
I would REALLY recommend sticking to the dark chocolate in the base (70%+ cocoa content) for the best bake
You can use any Toblerone you want for this recipe
I would recommend baking the brownie batter immediately once made for best results
The recipe has been updated to use a smidge more flour and cocoa powder for better results. The original recipe is still great using 90g flour and 35g cocoa powder